Buffer for longitudinally driven members



July 22, 1947. J, K. MORRIS BUFFER FOR LONGITUDINALLY DRIVEN MEMBERSoriginal Filed March 1, 15543 2 sheets-sheet 1 [I2 Uenfor: JOHN K Mom/5.1/fon? y July 22, 1947. J, K, MORRlS 2,424,492 BUFFER FORLONGITUDINALLY DRIVEN MEMBERS Original Filed March 1, 19413v 2Sheets-Sheet 2 [n I/ezor.'

JOH/V K. MORRIS *By AM/mm1? Patented July 22, 1947 BUFFER FORLONGITUDINALLY DRIVEN MEMBERS John K. Morris, Los Angeles, Calif.

Original application March 1, 1943, Serial No.

1944, Serial No. 530,535

Claims. (Cl. 74-424.8)

This invention relates to a driving means and particularly pertains to abuffer for longitudinally driven members and is a division of mycopending application Serial No. 477,669, entitled Gear power unit,filed by me March l, 1943.

In the operation of various types of mechanism it is desirable toprovide a mechanical structure by which a rotating drive motion will betranslated into a lineal movement; of a driven member, and between whichdrive and driven elements a suitable powerv increase will be obtained.Such structures are of particular value at the present time for remotelycontrolling parts of airplanes, as for example the control flaps of theairplanes by which the wings are trimmed. In such structures anindividual drive motor is provided, assembled with a housing withinwhich a train of rotary gears is mounted and through which gears areciprocating driven shaft is actuated, the motor circuit beingcontrolled from the instrument panel of the airplane. In view of thefact that the motor and gear unit may be disposed at points remote fromthe control switch, and that the operation of the unit cannot beobserved, it often occurs that the driving motor will be operating athigh speed when the reciprocating driven shaft has reached the end ofits stroke, with the result that the parts of the structure may bejammed or broken.

It is the principal object of the present invention, therefore, toprovide a buffer structure interposed between a relatively xed supportand a longitudinally driven member, whereby the driven member may berestrained in operation at the ,end of its stroke to bring it to restwithout damage to the relatively movable parts.

The present invention contemplates the provision o`f a housing withinwhich a member longitudlnally reciprocates while held against rotation,said reciprocating member carrying a nut engaging a rotatable screwextending longitudinally thereof, the screw being iitted with buiiermeans adapted to be engaged by stop shoulders adjacent opposite ends ofthe reciprocating member, whereby the reciprocating member will berestrained in its movement at opposite ends of its stroke in a manner toabsorb the force exerted longitudinally in driving the reciprocatingmember.

The invention is illustrated by way of example in the accompanyingdrawings in which:

Figure 1 is a view in central longitudinal section through the gearpower unit with which the present invention is concerned, and disclosesthe Divided and this application April 11,

reciprocating driven member and the drive therefor.

Fig. 2 is a view in transverse section through the housing of thestructure showing the rotary gear train as seen on the line 2-2 in Fig.1.

Fig. 3 is an enlarged fragmentary view in section and elevation showingthe tubular case and the outer end of the operating connection throughthe reciprocating member.

Fig. 4 is a fragmentary view in longitudinal section showing a modifiedform of buffer including anti-friction bearings,

Referring more particularly to the drawings, a type of structure isshown with which the buffer is intended to operate and in which drawingsIII indicates a driving motor. This motor is here shown as being anelectric motor and it is of course controlled by a suitable electriccircuit and electric switch. The switch is disposed at a point remotefrom the unit with which the present invention is concerned. It isunderstood that any other type of prime motor might be used if desired.The motor is mounted upon a bolting flange II and is secured in place byscrews I2. The bolting flange is part of a gear case I3. This gear casehas a forward wall I4 formed with an opening I5 through it in axialalignment with the motor III. The drive shaft IB of the motor extendsthrough this opening and carries a driving pinion I'I. This pinion is aworm which is in mesh with a worm wheel I8. The worm wheel I8 is mountedupon a shaft I9 which is disposed at an angle to horizontal, and thusmakes it possible for the gear case `I3 to be of unusually smalldimensions -while accommodating various gears to be hereinafterdescribed. The shaft I3 is mounted at its uppermost end in a bearing 20and at its lowermost end in a bearing structure 2l. The bearingstructure 2| is directly included within a cap 22 secured within a bore23 of the housing I3 by cap screws 24. Mounted uponthe shaft I9 orformed integral therewith is a worm 25. This is in mesh with a wormwheel 26. 'Ihe worm wheel 26 is secured upon a longitudinally extendingdriven shaft 21,

'I'he driven shaft 21 is here shown as disposed in the same axial planewith` the drive shaft I6 and is parallel thereto. The shaft is ofconsiderable length as compared with the length of the shaft [B and themotor I0 and extends forwardly of the motor. For convenience isdescription only, it is to be understood that the motor I0 is disposedhorizontally. and that the entire unit functions with the motor I0 andthe shaft 21 lying in parallel horizontal planes. It is understood,however, that the unit may be disposed in any required position inactual operation.

The shaft 21 has a reduced portion 28 which terminates in a threaded end29, and a suitable anti-friction bearing 30 is mounted on the reducedportion 28 and is carried within a cage 3l. The cage 3| is mountedwithin a. bearing portion 32 of a cover plate 33, which is secured tothe gear case I3 by cap screws 34 and is disposed parallel to the frontplate I4 of the gear case. The worm gear 26 is mounted upon the reducedportion of the driven shaft 21 and is keyed with relation thereto. A nut35 engages the threaded end 29 of the shaft and supports the shaft withrelation to the bearing 30.

Secured over the end of the bearing portion 32 of the cover plate 33 isa cap 36. This is formed with a lug 31 to receive pivot pin 38 by whicha suitable connecting member (not shown) is attached to the gear caseand either supports the case or provides an operating connectiontherewith.

The forward face I4 of the gear case I3 is formed with a tubular bearingportion 38 through which the shaft 21 extends. Anti-friction bearings 40are mounted within this tubular portion and support the shaft. Theposition of these bearings is slightly in advance of the reduced portion28 of the shaft.

Extending outwardly from the front face of the wall I4 of the gear caseI3 is a boss 4I. Secured firmly within the bore y42 of the boss is atubular housing 43 which is rigidly supported in position and throughoutthe length of which a threaded portion 44 of the driven shaft 21extends. At the inner end of the tubular housing 43 and within the bore42 is an annular packing ring 45 which forms a fluid-tight seal aroundthe driven shaft 21 and prevents leakage of the grease or otherlubricant with which the gear case I3 is packed. Reciprocably mountedwithin the tubular housing and around the portion 44 of the driven shaft21 is a thrust sleeve 46. This sleeve has a sliding fit in relation tothe bore of the tubular housing 43. The outer end of the thrust sleevereceives a yoke 41 which is held in place by cap screws 48. This yoke isformed with a transverse bore 49 to receive a suitable connecting pin bywhich the yoke is attached to a device to be actuated, such for exampleas a wing flap (not shown in the drawing).

The outer end of the tubular housing is formed with a packing gland 50which circumscribes the thrust sleeve 46 and forms a fluid sealtherewith. The inner end of the thrust sleeve is formed with a tubularnut I which is secured to the sleeve by any suitable means, such aswelding. This nut has a central threaded bore engaging threads on thesection 44 of the driven shaft 21. Thus, as the shaft 21 is rotated thenut will move therealong and will simultaneously reciprocate the thrustsleeve 46,. It will be evident that as the shaft 21 rotates to move thethrust sleeve 46 to the extreme end of its stroke in either direction,the shaft 21 may possibly continue to rotate and exert a longitudinalmovement upon the thrust sleeve 46, since the circuit of the motor IIImay still be closed. In order to resist this movement a snubberstructure is provided, as generally indicated at 52. This structure ismounted upon a reduced end portion 53 of the section 44 of the drivenshaft 21 and includes a deformable washer 54 disposed between sets ofwashers 55 and 56.

The deformable element 54 is preferably made of some synthetic rubber,such as "neoprene" The washers 55, directly contacting the oppositesides of the neoprene disc or ring, are preferably formed of brass orbronze. The opposing faces of the washers 55 are concave, as indicatedat 51, and the diameter of the washers 55 is greater than the diameterof the neoprene disc 54, for a purpose to be hereinafter described. Theouter faces of the discs 55, as indicated at 58, are flat and in planesnormal to the longitudinal axis of the shaft 21. Similar contiguous flatfaces 59 are formed upon the discs 56. These discs are preferably madeof steel, and the contiguous faces 58 and 59 are ground smooth. A lm ofgrease is disposed between the contiguous faces 58 and 59 to facilitatein relative rotation of the discs 55 and 56. A nut 6U is threaded ontothe outer end of the portion 53 of the shaft 21 and holds the members54, 55 and 56 in assembled relation to each other upon the shaft.Attention is directed to the fact that the diameters of the discs 55 and56 are larger than the diameter of the threaded portion 44 of the shaft21, and that they are also larger than the outside dimensions of the nut60. The innermost disc 56 thus presents an inner face 6I to end face 62of the nut 5I which is assembled with the thrust sleeve 46. The outerface 63 of the outer disc 56 may be encountered by a stop face 64 formedas a part of the yoke 41, as shown in Fig. 1 of the drawings. It is tobe understood that the connection between the yoke 41 and the memberoperated by the yoke, and which is attached by a pin 65, holds the yokeand the thrust sleeve 46 against rotation. This likewise acts to holdthe nut 5l against rotation,

so that rotation of the driven shaft 21 will impart longitudinalmovement to the nut 5I and the thrust sleeve 46.

When it is desired to use the device as here shown, the parts are builtand assembled as described in the foregoing specification. After thestructure has been assembled as shown, the motor I0 may be operated.This will impart rotation to the drive shaft I6 and the worm I1, whichin turn will rotate the worm gear I8 in the direction of the arrow a, asshown in Fig. 1. The worm 25 will then be driven and will impartrotation to the Worm wheel 26 in the direction of the arrow b, as shownin Fig. 2. As this takes place the threaded engagement of the portion 44of the shaft 21 with the nut 5I will cause the thrust sleeve 46 to moveoutwardly in the direction of the arrow c, as shown in Fig. l, and willproject it from the end of the tubular housing 43. This action willcontinue until the end face or shoulder 62 of the nut 5I will encounterthe face 6I of the steel washer 56. The tendency will thus be for theIshaft to continue to rotate while the nut binds against the end face ofthe washer 56. 55 and 56 will tend to rotate with relation to eachother, thus dissipating the torque force of the driven shaft 21, andwill also tend to deform the disc 54 which is positioned between thewashers 55. In view of the fact that the disc 54 bears against concavefaces 51 of the discs 55, there will be a. tendency for the outercircumference of the disc 54 to be confined between the washers Incidentto this action the washers.

vdirection to 'that indicated by the arrow b in Fig. 2, the thrustsleeve 46 will move in a counterdirection to the arrow c in Fig. 1. Thiswlllcontinue until the shoulder 64 on the yoke 14 abuts against theouter face 63 of the outermost disc 56.

The same snubbingaction will then be obtained as previously described.

In actual operation of a device employing the structure here disclosedthe motor Illldrives the shaft at high speed and thus with considerableforce the moving mass therefore attains appreciable inertia. This may beproduced by the normaldriving force and speed of operation, when anoverload conditions prevails or when the motor continue to drive afterthe end-of the reciprocating stroke. Under any of the foregoingconditions the buffer structure will strike one of the stops violentlyand the buffer must then act to bring the relatively moving parts torest. This requires resistance to torque force as well as thrust ofconsiderable magnitude. In practice heretofore metal buffer elementswhen used alone have been shattered by these forces. It was only whenyieldable resistance to torque and thrust was pr'of Referring to Fig. 4of the drawings, it will be l' seen that anti-friction bearings 65' areinterposed between the discs 55 and 56.

It will thus be seen that the structure here disclosed provides arotatable screw-carrying afnut and which nut is fixed t`o alongitudinally sliding member held against rotation, the screw carryingmeans for damping its rotation and the longitudinal movement of the nutat opposite ends of the travel of the longitudinal member, said actionbeing brought about by simple and effective means which are not liableto get out of order and which will insure that the movable parts will bebrought to rest promptlyA without strain when the opposite ends of thestroke of the longitudinal member have been reached. ,K

While I have shown the preferred form of my invention as now known tome, it will be understood that various changes may be made incombination, construction and arrangement of parts by those skilled inthe art, without departing from the spirit of my invention as claimed.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. A buffer structure of the character described, comprising anon-metallic deformablel disc mounted upon a shaft, a pair of metallicfalloy discs, one disposed on each side of the deformable disc on theshaft. and a pair of steel discs disposed upon the shaft, one againstthe outer face of each of the alloy discs, the bearing surfaces of saidmetallic discs being ground to a desired degree of smoothness. ,y

2. A buffer structure adapted to be mounted upon a rotatable shaft whichextends into a nonrotatable tubular member having reciprocable movementwith relation to the shaft and carrying fixed spaced abutments betweenwhich the buffer structure is disposed. said buffer comprising a centraldeformable disc freely mounted upon said shaft, pairs of rigid discsfreely mounted upon said shaft, a pair of said discs being disposed oneach side of the deformable disc with the innermost disc bearing againstthe deformable discs and the rigid discs bearing against each other,said rigid discs having limited longitudinal movement upon the shaft andbeing free to rotate therearound whereby pressure exerted by either ofsaid stops against an abutting rigid disc will be imparted to thedeformable disc and relatively longitudinal and rotational movementbetween the shaft and the tubular element willbe resisted. j

3. 'I'he structure of claim 2 wherein the faces of the innermost rigiddiscs `presented to the opposite side faces of the deformable disc areconcave.

4. lA buffer structure adapted to be mounted upon a rotatable shaft anddisposed within a nonrotatable tubular element, said shaft and tubular'element having relatively longitudinal movement.

the tubular element carrying stops between which the buffer structure isdisposed and by which relatively longitudinalmovement is limited, saidbuffer comprising a central deformable disc freely mounted upon saidshaft, pairs of rigid discs freely mounted upon said shaft. one at eachend of said deformable disc, the rigid discs of each pair/including arelatively soft metal disc bearing against the end face of thedeformable disc and a relatively hard metal disc to encounter one ofsaid' 5. The structure of claim 4 wherein thefaces oi' the relativelysoft rigid discs which bear against the deformable discs are concave.

JoHN K. MORRIS.

aEFEnENcEs CITED The following references are of record in the nie ofthis patent:

UNITED STATES PATENTS y Number Name Date Y,

2,252,789 Van Dorn Aug. 19, 1941 2,349,332 Angell May 23, 1,944

FOREIGN PATENTS Number f Country Date 39,036 Netherlands Sept. 15, 1936

